Alternating-current block-signal system.



PATENTED NOV. 6, 1906.

M. R. HANNA. 1 ALTERNATING CURRENT BLOCK SIGNAL SYSTEM.

APPLICATION FILED AIR.26.1906.

Q lllllll ll E mw I M MA mwm Mi w M WM S w w x R gp Q M}? M h m k m v JF llllllll 1 m H d w r n t 0 n A 6 m? HHHHH V llll MM 0X """HHHHHH U W IW u 3 HHHHHHHHT l V/Zi/vesses;

- UNITED STATES PATENT OFFICE.

. MAX R. HANNA; OF soHENncrinY, NEW YORK, ASSIGNOR TO GENERAL ELE TRIOCOMPANY, A CORPORATION on NEW YORK.

ALTERNATING-CUIL-RRENT BLOCK-SIGNAL SYSTEM.

Specification ofietteirs Batent.

Patented Nov. 6, 1906.

Application filed April 26, 1906 Serial No. 813,809.

To all whom, it may concern: I

.- Be it known that I, MAX R. HANNA, a citizen of the United States,residing at Schenectady, county of Schenectady, State of New York, haveinvented certain new and useful Im rovements in Alternating-CurrentBlockignal Systems, of which the following is a specification.

My invention relates to alternating-current signal systems, such as havebeen pro- Bedell March 20, 1900, and April 17, 1900.

'With either connection the failure of a single insulating-joint willclose a circuit from the sup ly-transformer of one block to the otherblodlr, so as to energizethe track-relay. Be.- cause of this there isdanger of- Obtaining a clear indication from a signal while a train isin the block, the relay being energized from the preceding block throughthe defective insulating joint but this can ordinarily be readilyavoided by connecting the supplytransformers of alternate blocks reversey, so that in case an insulating-joint fails the current supplied to therelay will be of a phase opposite to normal, so that by employing a vtrack-transformers an relay of a type responslve to a reversal of phasethis leakage-current acts only to hold the relay in its 0 en-circuitposition. Similar. connections have been employed with batteries andpolarized relays in direct-current signal systems. This arrangementremoves all danger from leaka e-current as long as all the blocks aresupp 'ed with signal-current from the same source. quently happens,however, that it is desirable to section the sup ly-conductors for the dconnect them to' different-stations, which may sometimes 0 erate inparallel and sometimes not. en the two'stationsare not operating inparallel,

It fre it is evident that the relative phases of the voltages on thesupply-conductors are indeterminate, and consequently the arrangementoutlined above by itself would not insure against trouble fromleakage-currents between two adjacent blocks su plied from difierentstations.

to that end I insert between the two adjacent blocks supplied from'diflerent stations a The object of my invention is to take care of thiscontingency, and

short track-section with its supply-trans- 1 former'conn'ected to thesame con uctors as the supply-transformer of one of the two adjacentlocks and connect it op Ositely with respect to .that transformer, an Iprovide a relay for the short track-section and interlock it with therelay of the adjacent block supplied from the same conductors, so thatthe two relays jointly control the signal for that block. In thismanner, as will appear from the following explanation, all danger.

from leakage-currents is avoided.

My invention will best be understood by reference to the accompan 'ngdrawing, which shows diagrammatica y an alternating-current signalsystem arranged in accordance with my invention.

' In the drawing, A A A represent the rails of three blocks of thesystem.

B represents a third rail or other supplyconductor for,power-current.

C 0 represent alternating-current-supplyconductors, which-may beconnected to different stations.

D D D represent transformers connected to the supply-conductors and S11plying signal-current to the track-circuits of the blocks. E E representtransformers having their primaries connected to the track-circuits andtheir secondaries connected to one phase of the track-relays, which areshown as of the polyphase induction type. Thus the windin F of thetrack-relay for the block A is supp ied from the secondary oftransformer E, while the other phase G is supplied directly from theconductors C.

H represents a short-circuited'secondary member adapted when both phasesof the relay are energized with currents of proper phase to close thecircuit of the operating mechanism I of the signal J A relay of scribedabove is not sufficient for protection.

this type is responsive to a reversal. of phase in either winding-thatis, if the phase of the current in winding F should be reversed thetorque in the secondary member would tend to move it away fromclosed-circuit position, so as to put the signal at danger.

The central point of the secondary of transformer D is connected to thecentral point of the transformer E, so as to afford a path for theowercurrent, and the other blocks are simi arly connected, this beingthe equipotential connection described in the Bedell patents beforementioned.

It will be observed that transformers D and D are oppositely connectedto the supply-conductors, Consequently if the upper conductors C beassumed positive at a glven instant the directions of current-flow inthe several circuits will be as indicated by the arrows. As shown by thearrows, the currents in the primary of transformer E and in thesecondary of transformer D are normally in the same direction. Now ifeither of the in I sulating-joints between blocks A and A should failone-half of the secondary oftransformer D would be.short-circuitedon-onehalf of the secondary of transformer E, and with a train in .blockA the current that might flow through this short circuit might besufficient to supply to the relay-windlng F a current of practicallynormal amount; but this current will be of a phase the reverse ofnormal. Consequently, as has been explained heretofore, the only effectthat it could have upon the relay would be to hold it all the morefirmly in off position. Thus by properly connecting thesupplytransformers'for the blocks and by using relays of a type resonsive to a phase reversal all danger from eaka e-currents is avoided aslong as all the bloc s are supplied with current from the same source.This alternately reverse connection of the supply-transformers is thesame that has been employed with batteries in direct-current systemswith polarized relays and has been described at len th only for thepurpose of giving a clear unferstanding of my invention.

' In the casepf two adjacent blocks supplied from' separate stations thearrangement de- For instance, if conductors C, supplying the block A,are connected to one station and conductors C, sup lying 'the block Aare connected to 'anot er station, and the two stations are not operatinin parallel, it is ohvious that the relative phases of the voltagessupplied to the two track-circuits A and A by the transformers D and Dwill be indeterminate. In order to avoid the danger fromleakage-currents in such a case, I insert the short track-section abetween the blocks A and A and supply this short section from atransformer (1*, connected tothe con ductors C, from which the'block Ais sup plied. By oppositely connecting D and d all dangerofleakagc-current due to a clefective insulating-joint between block Aand section a is avoided, so hat the secondary member II is always inoff position as long' as a train is in block A The contacts of relaymember H are connected in series with the contacts of the relay memberif of the short track-section, so that the signal J can give a clearindication only when both relays are in closed-circuit position.Consequently,

although a defective insulating-joint between the short track-sectio'iand block'A might hold the relay member h in closed position, even witha train in the short section, this isnot a source of danger, since thesection may be made soshort that a train will enter block A before ithas left block A. Consequently relay member II will open before rela Tmember H has closed, so that the train will always have a danger-signalbehind it.

I do not desire to limit myself to the par ticular construction andarrangement of parts here shown, but aim in the a pended claims to coverall. modifications W ch are within the scope of my invention.

-What I claim as new, and desire to secure by Letters Patent of the.United States, is

1. In an alternating-current block-signal system, transformers supplyingsignal-current tothe track-circuits of the blocks, separatesupply-conductors for the transformers of two adjacent blocks, a shorttrack-section inserted between said two blocks, a supplytransformer forsaid short section connected to the same supply-conductors as the transjformer of one o sitely connected with respect to that transformer, tworelays su plied with alternating current respectively om the shortsection and from the adjacent block that is supplied from thesamesupplyconductors, said relays being responsive to a reversal of phase ofsaid current, and a signal controlledby said relays jointly.

2. In-an alternating-current block-signal system, transformers supplyingsignal-cur rent to the track-circuits of the blocks, separatesupply-conductors for the transformers the two blocks and oppo-' of twoadjacent blocks, a short track-section inserted between said two blocks,a supplytransformer for said short section connected to" the same suply-conductors as the transformer of one o the two blocks and oppositelyconnected with respect to that transformer,

two polyphase relays having one phase supplied respectively from theshort section and from the adjacent block supplied from the samesupply-conductors, and a signal controlled by said relays join tly.

adjacent blocks supplied from difierent 0011- system, a plurality ofsets of signal-currentductors. :0. supply conductors, transformersconnected In Witness whereof I have hereunto set. my to said conductorsand supplying the trackhand this 25th day of April, 1906. circuits ofthe blocks, the transformers of ad- MAX R. HANNA. jacent-blocks suppliedfrom the same supply- Witnesses:

conductors being oppositelyj connected, and BENJAMIN B. HULL,-

a shqrt raihsectlon mterposed'between' two HELEN ORFQRD.

3. In an alternating-current block-signal

